function ret = densityFunction1(lower,upper)
    global W;
    global U;
    global SIGMA;
    ret = quad(@npdf,lower,upper);
    function y = npdf(x)
        y = W(1)*1./(sqrt(2*pi)*SIGMA(1))*exp(-(x-U(1)).^2/(2*SIGMA(1)^2)) + W(2)* 1./(sqrt(2*pi)*SIGMA(2))*exp(-(x-U(2)).^2/(2*SIGMA(2)^2)) + W(3)*1./(sqrt(2*pi)*SIGMA(3))*exp(-(x-U(3)).^2/(2*SIGMA(3)^2));
    end
end